It is unlikely that losses in homeostatic control of physiological function during ones life span are due purely to the inherit process of aging. That is, an individual's "lifestyle", in particular dietary habits, must be considered as a variable in the aging process. Indeed, caloric and protein restriction in rats improves longevity and delays the onset of functional loss and/or major pathological lesions. On the other hand, a possible deleterious effect of increasing a specific macronutrient component of a rat's diet on life span and physiologic function has not been widely investigated. As measures of this effect, we propose to evaluate the longevity characteristics and the regulation of endocrine pancreatic function in aging rats fed low and high sucrose diets. We hypothesize that male Fischer 344 (F344) rats fed high sucrose diets (60%) will have shorten maximal and median life spans, development hyperinsulinemia, and that, this hyperinsulinemia will reflect a loss in central nervous system (CNS) control of endocrine pancreatic function. To test these hypotheses, we have designed experiments to: 1) compare the life span characteristics and cause of death of male F344 rats fed a high sucrose diet ad libitum to those rats fed a low sucrose diet ad libitum, and pair-fed high sucrose, 2) determine the insulin secretion rate of aging rats by ,utilizing an in vitro isolated pancreatic perfusion system, 3) evaluate the central nervous systems-(CNS) control of insulin secretion with aging by using an in situ CNS-intact pancreatic perfusion technique in younger and older male F344 rats, and 4) using the same in situ technique, evaluate the effect of long-term high sucrose feeding on the autonomic nervous system's control of insulin secretion.